<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Score</title>
</head>
<body>

    <script>
        Number.prototype.score = function(r){
            
            return this.toFixed(r);
        }
        var num = 12;
        console.log(num.score(2));
    </script>
    
</body>
</html>